118 M. van Tieghem on the Amylacecous Globules 
form is spherical or ovoid ; sometimes they are flattened and dis- 
coidal or lenticular in form, sometimes irregular. They are 
formed by a very distinct colourless or rose-coloured membrane, 
filled with solid greyish contents, most frequently without any 
eentral space, but sometimes with a cavity im the centre, which 
it is not unusual to see divided into several compartments. The 
full globules are of two kinds: some, and by far the greater 
number, have a circular outline and are simple; their contents, 
apparently homogeneous, are formed of very delicate concentric 
zones, and give a very clear black cross in the polarizing ap- 
paratus; the others, variable in form and aspect, are composite, 
and show a system of concentric layers and a black cross in each 
of their compartments, when these are sufficiently large. 
The very variable dimensions of these globules is in relation 
to their degree of development: the ordinary diameter of the 
well-developed grains is from 0:0138—0:015 millimetre; the 
maximum observed was 0:025 millimetre. Iodine gives them 
a reddish-yellow colour. This tint persists upon all the globules 
whatever be the quantity of tincture of iodine employed; but 
when we renew the liquid which bathes the grains im proportion 
as it evaporates, replacing it alternately by a drop of tincture of 
of iodine and a drop of water, at the edges of the covering glass, 
where the osmotic movements produced by an alternate disic- 
cation and humectation with liquids of different densities are 
most active, we see the globules become altered in a remarkable 
manner at the same time that their colour changes. Sometimes 
there appears at the centre a small circular space, which enlarges 
by degrees, the layers becoming dissolved successively from 
the centre to the periphery, at the same time that the globule 
enlarges and becomes discoidal; it is reduced at last to a 
membrane, which becomes more and more delicate, entire or 
irregularly torn, and as the granule becomes empty its tint 
passes to pure violet. In other cases the solution commences 
by a circle of small holes, which increase radially, remaining 
separated by solid rays; the centre is at the same time hollowed, 
and the outer membrane, being unable to yield equally to the 
inflation, becomes undulated; the globule is then of a fine 
violet, and presents the aspect of a wheel, of which the nave, 
the spokes, and the undulated felly are of a deep violet, and the 
intervals of a lighter tint. In the composite globules, formed of 
compartments arranged in a circle round a central chamber, 
the contents of each compartment become dissolved by de- 
grees, the granule swells, becomes of a fine violet colour, and 
presents the radiated appearance which I have just described, 
with still more distinctness. This disorganization of the gra- 
nule with blue coloration may, however, be produced rapidly. 
